You can totally extrude both narrower and wider than your nozzle. Heck, if you have a Slic3r based slicer like PrusaSlicer, Orca, SuperSlicer, etc and your extrusion width is expressed as a percentage, that percentage is a percentage of layer height - NOT nozzle diameter.

If you’re using 0.2mm layers, your extrusion with is expressed as a percentage, and you’re using a 0.4mm nozzle your extrusion with is less than your actual nozel diameter.

I print most of my prints with a 0.4mm nozzle and 0.6mm extrusion width.